Auxiliary device for zig-zag sewing machines



March 1, 1960 H. ISLER 2,926,621

AUXILIARY DEVICE FOR ZIG-ZAG SEWING MACHINES Filed March 15, 1956 Fig.5

AUXILIARY DEVICE FOR ZIG-ZAG SEWING MACHINES Hans Isler, Zug, Switzerland, assignor to Nahma A.G., Zug, Switzerland, a firm The invention relates to an auxiliary device for zig-zag sewing machines for the production of hollow seam.

There exists a zig-zag sewing machine for industrial purposes in which such an auxiliary device is provided;

the same consists of a special foot adapted to be fixed to the presser rod, and of a special stitch plate which comprises a distance holder for the two pieces of fabric to be connected with one another by the hollow seam.

The auxiliary device according to the invention is distinguished therefrom in that it comprises a foot sole for the guidance of the fabric provided with a stitch hole on which a distance holder is mounted resiliently and pendulum-fashion which comes to lie between the two pieces of fabric to be connected by means of the hollow seam, and thereby keeps them spaced apart from one another.

This auxiliary device has the great advantage that the stitch plate of the sewing machine need not be ex changed. It canbe mounted inexpensively and simply, so that it can be provided advantageously also for household sewing machineshaving zig-zag devices.

In the accompanying drawing an embodiment of the invention is illustrated, in which:

Fig. 1 is a front elevation of the auxiliary device,

Fig. 2 is a lateral elevation to Fig. 1, and

Fig. 3 is a plan view to Figs. 1 and 2.

Fig. 4 is a lateral view of the general arrangement of the auxiliary device as fitted to a sewing machine.

Fig. 5 is a section on the line 5--5 of Fig. 3.

The auxiliary device comprises a foot sole 1 which is provided on top with two lugs 2. In these lugs bores 2' are provided through which a pin can be pushed in order to attach the foot sole 1 to the foot barrel of the presser rod 14 of a household sewing machine having a zig-zag device. The foot barrel 15, which comes to lie between the lugs 2, and the pin 16 attaching the same to said lugs are shown diagrammatically in Fig. 4.

The foot sole has at its forward end two projections 3 which are slightly curved upward. Between the same is a slot 4 which'reaches right up to the stitch hole 5 through which the. needle can move up and down.

In the slot 4 a distance holder 6 is arranged which is provided with a vertical blind hole 7 and two vertical slots 8 in the wall of the distance holder 6. A pin 9 passes through these slots and rests with its ends in two spacedbrackets 10 formed on the foot sole 1.

A compression spring 11 bears with one end on the bottom of the blind bore 7, and with its other end on the middle portion of the pin 9, whereby the distance holder 6 is forced into the position shown in Figs. 1 and 2, in which the pin 9 is pressed by spring 11 to abut on the upper ends of the slots 9. The distance holder 6 is accordingly sprung and moreover suspended pendulum-fashion on the pin 9 of the foot sole 1. The frontal part 12 of the distance holder 6 is rounded, and at the rear the distance holder is flush with stitch hole 5.

In Fig. 1 the pieces of fabric 13 are indicated dia- United States PatetitfjOice 2,926,621 Patented Mar. 1, 1960 as well known, so that then the foot sole 1 comes to lie just above the pieces of fabric 13, whereby their guidance is secured. At this stage the distance holder 6 which rests on the stitch plate 17 moves upwardly rela tiveto the foot sole 1. Owing to its resilient and pendulum-fashion mounting the distance holder 6 adapts itself at the underside accurately to the stitch plate 17 so that the pieces of fabric are on no account liable to come between the stitch plate 17 and the distance holder 6.

When performing the usual zig-zag movement the needle comes to stand once over one and once over the other piece of fabric 13, where it performs one stitch at any time. The sections of thread bridging the distance between the pieces of fabric 13 then form the hollow seam desired. 7

Depending on the possibilities of the zig-zag device and/or of the sewing machine the following manners of stitches can be executed for example: an arcuate hollow seam stitch, a single needle hollow seam stitch, a double needle hollow seam stitch, a double hollow seam back stitch, a hollow seam wide stitch (baste seam).

The foot sole 1 is preferably made of a drawn profile bar, the profile of which is shown in Fig. 2. After a piece of the width shown in Fig. 3 has been severed off the profile bar, the lugs 2 and the bearings 10 are machined off by milling in the longitudinal direction. Thereafter the slot 4 and the hole 5 are made and the pivot holes are drilled. Instead of making the foot sole from metal it may consist at least in part of a transparent synthetic substance (see Fig. 5) in order that the pieces of fabricmay be better observed in operation. The distance holder may also be made transparent if desired.

While I have herein described and illustrated in the accompanying drawing what may be considered a typical and particularly useful embodiment of my said invention I wish it to be understood that I do not limit myself to the particular details and dimensions described and illustrated, for obvious modifications will occur to a person skilled in the art. I

What I claim as my invention and desire to secure by Letters Patent, is:

1. An auxiliary device for zig-zag sewing machines for the production of hollow seams comprising a foot sole for the guidance of the fabric, said foot sole being provided with a stitch hole and having two spaced brackets, a distance holder having upper and lower ends and a vertical blind bore therein between its two ends, the lower end of said distance holder normally projecting below the bottom surface of said foot sole, said distance holder also having two oppositely positioned vertical slots extending therethrough into its blind bore, each said sl-ot having a dimension smaller than the corresponding dimension of the bore, a pin supported in said brackets and extending through the slots in said distance holder, and a spring in the bore of said distance holder compressed between the bottom of the bore and middle portion of said pin to press said distance holder downwardly, whereby said distance holder is resiliently mounted on said foot sole and is guided and biased vertically downwardly to space apart two pieces of fabric to be sewn together. I

2. An auxiliary. device for zig-zag sewing machines for the production of hollow seams comprising a foot sole for the guidance of the fabric, said foot sole being provided with a stitch hole and having at its forward projection thereon, atdistance holder in said slotfi'n .ad-

vance of said stiteh hole and having two ends .anda

pressed between the bottom of the bore and the middle "portion bf'said pin to press said distance'holde'r downvertical blind bore therein "between its two ends, said I distance holder also having two oppositely positioned vertical slots extending therethrough into its bl-indbore, a pin supported by the brackets and extending through the slots in said distance holder, each slotin said distance holder having a dimensionsmaller than the .correspondingdimension of the boreland "having upper and lower ends spaced a distance apart greater than ft'he'dis-w tance between said pin and the bottom of said foot sole, and a spring in thebore of said distance holder com wardly between the two projections at the forward end of said foot sole and to bring the lower end of said distance holder below the bottom surface of said foot sole; whereby said distance holder is resiliently mounted on said foot sole in advance of. the stitch hole therein and is guided and biased vertically downwardly to space apart two pieces of fabric'to he sewn together.

' References Cited in the file ofthis patent UNITED, STATES BATENTS 2384;454 Cosentino ,Sept., ll, 1945 "2,487,285 Voigt Nov. 8, 1949 2,570,464 Oct. 9, 1951 

